This invention relates to a method of manufacturing a 3D viewing disk.
A known type of 3D viewing disk which can be fitted in a stereoscopic viewing device, such as the device sold under the designation VIEWMASTER, is made of stiff opaque sheet material and is formed with 14 substantially rectangular apertures which are equiangularly spaced about, and are equidistant from, the center of the disk. Seven pairs of transparencies, representing left and right stereoscopic images respectively of seven scenes, are accommodated in the 14 apertures respectively.
The stereoscopic viewing device has two eyepieces for viewing simultaneously, with the left and right eyes respectively, one pair of transparencies so that the user can view a 3D image of the scene. The viewing device includes an advancing mechanism which engages indexing holes in the disk for rotating the disk to seven indexed positions allowing the user to view 3D images of the seven scenes in succession.
The opaque sheet material may be two cards which are made of paperboard material and are glued together with the 14 transparencies held between the cards.
In one practical method of manufacturing a 3D viewing disk, a 3D camera is used to capture left eye and right eye images of a scene on photographic transparency film. The transparency film is then used to generate corresponding internegatives and the two internegatives of one pair are mounted on a carrier in carefully controlled relative positions and orientations. The carrier is placed in an optical printer which makes multiple copies of the left eye image and multiple copies of the right eye image on respective rolls of receiving film. The carrier serves to position the internegatives precisely relative to the frame of the receiving film, and accordingly the images are located with a high degree of precision relative to the frame of the receiving film. The rolls of receiving film are die cut into individual transparencies and the left and right eye transparencies for a given scene are attached to a first of the two cards using registration elements to ensure that the two die cut transparencies are in the proper relative positions and orientations. The left and right eye transparencies for the next scene are then attached to the first card, and so on until all seven pairs of transparencies have been attached to the first card. Finally, the second card is attached to the first card and the 14 transparencies are then held securely between the cards.
3D viewing disks of the kind described above are used as toys, in which case many thousand copies of a given disk might be made. However, the 3D viewing disk has also found a market in short runs as a promotional tool, and in this case the purchaser may require as few as ten copies.
The conventional method of fabricating a 3D viewing disk requires complex machinery which must be maintained and adjusted to ensure that the die cut transparencies will be properly positioned in the completed disk. The cost per disk of manufacturing a long run of disks is very low, but the nature of the manufacturing process makes it expensive to manufacture a short run of disks. Further, the lead time required to obtain a short run of disks is long.